Process of refining wood rosin



July 2, 1929 H. E. KAISER ET AL 1,719,431

PROCESS OF REFINING WOOD ROSIN Filed May 15, 1925 2 sheeheet 1 ROS I N POT C I 1 To VACUUM ,4770/WVEY,

July 2, 1929. H. E. KAISER ET AL 1,719,431

PROCESS OFREFINING WOOD ROBIN Y Filed May 15, 1925 2 Sheets5heet 2 lll 1 SEPARATING TANK Patented July 2, 1929.

UNITED STATES i 1,719,431 PATENT OFFICE.

HARRY E. KAISER, OF RENVIL, ANDARTHUR LANGMEIER, OE DOVER, NEW JERSEY, AssIeNoRs 'ro HERCULES POWDER COMPANY, OE WILMiNG'rON, DELAWARE, A

CORPORATION OF DELAWARE.

PROCESS OF REFINING WOOD ROSIN.

Appiieation sled May 15,

The object of our invention is to so treat wood rosin as to provide a rosin so highly refined that it is adapted for use in sizing the higher grades of paper, in the manufacture of better grades of varnish, and for other purposes for which a high grade rosin is adapted.

A known process of producing wood rosin of a lower grade, and the process that we preferably employ as apreliminary process in the manufacture of our' more highly rey fined rosin, consists in grinding wood and stumps from-pine trees, placing the wood vstock in large digesters, passing steam through the stock and thus drivin off a considerable quantity of turpentine, ooding the stock with gasoline or other solvent,

thereby extracting certain materials, chiefly rosin, pine oil and various color bodies, passing the gasoline solution, commonly known as drop liquor, through `suitableevaporators, and fractionally removing the gasoline and ine oil. The pine oil produced by the distillation isrgtined and sold. lThe recovered gasoline is again used in the process.

The recovered rosin is a marketable prody uct, but is satisfactory for sizing lonly the lower grades ol paper and in making the inferior grades of varnish, and therefore must be marketed at a relatively low price.

In our process We subject this lower grade rosin to a treatment which greatly improves thecolor of the rosin and imparts to it generally such high quality, both chemical and physical, as to adapt it for sizing the higher grades-of paper and forb use in the better grades of varnish.

To secure the best results we prefer to preliminarily 'distill the rosin to remove some of the objectionable coloring matter. This preliminary distillation is not essential in order to secure valuable results, but such preliininary distillation'insures a perhaps higher grade ultimate product an'd a conversion of a larger proportionl ofthe rosin into suchV higher grade ultimate product. e

After such ,preliminary distillation, the rosin is subjected to the direct action of steam in a stillunder a vacuum of within about two inches of the normal barometric pressure of mercury column. The rosin is at the same i time heated by means of oil maintained at a temperature of from 500 to 650 F.7-preferably within the higher part of this range.'

fractional condensers.

1923. serial Np. 639,054.

The distillation may be in batch or continuous. If in batch, the still may be surrounded l by av jacket in which a circulation of the hot oil is maintained. Ifthe continuous process 1s used, the rosin may flow over coils of pipe through which the hot oil is circulated.

The still vapors are then passed through Proper temperature tively free from rosin oi-ls and pine oils. At

this temperature a water-free product results and there is little danger of the condensed rosin crystallizing. Thus, if the rosin is passed through three condensers in which temperatures of about 400 F., 350 F. and 300 F. are maintained, the rosin that condenses inthe first condenser is of a very high quality and suitable for sizing the highest grade paper and for use in the veryfbest varnish. The product of the second condenser is a good rosin, while the product of thefthird condenser is of lower grade.

It is impossible, in these condensers, to condense all the rosin and rosin oil and we have therefore designed a scrubber for use at .the end of the condensing system. This scrubber comprises a number of tubes, arranged in series,l which receive the uncondensed rosin vapor or mist and through which circulates 'a stream of gasoline, kerosene or other solvent. `During the flow through the tubes, they are subjected to the action of cold water. In

these tubes the steam, rosin and rosin oilvapor are condensed. The tubes are connected with a tank in which the water and gasoline solution separate. The water is drawn oli' andK the gasoline pumped back to the solvent line. AfterI the gasoline solutin approaches the saturation point, it is separated fr m the rosin by distillation.

' The a ove is a general description of theS fectively heated by means of a coil d through Fig. lAis a similar viewof the remainder of the apparatus, comprising the fractional condensers and scrubber.

T lie rosin is first heated in a preheater a having a vacuum connection b by way'of a sma l condenser c. The preheater may be efproportions of this low boiling coloring maftter, the preliminary distillation will insure substantial Iuniformity in the material that vpasses to the main still.`

The still g is preferably of iron lined with aluminum and may be heated in any convenient manner, such as, preferably, by heated oil circulated through coils or, as shown in the drawing, through a jacket It. The oil p should'be at such temperature as to heat the rosin to atemperaure well over 500,? F. and preferably about 600 or 650 F. z' is the oil inlet and j the oil outlet. The bottom of the still is connected with a vessellc to receive residue.- It is preferred to inject superheated steam into the ody of the rosin in the still, al-

- though this improvement in the process is no part of our invention, having been conceived by George E.`Jenks, who has liled an application for patent therefor, Serial No. 639,062, dated May 1 5, 1923. F orJ this purpose, a steam pipe m extends into the still. Through this pipe superheated steam is discharged into the body of the rosinl in the still.

The still g is adapted to distill the rosin in batch, but ,it is equally practicable, and perhaps preferable, to distill the rosin continuously. In view, however, of the fact that the invention is not dependent upon the use of any particular apparatus, illustrations of the different constructions of stills that may be lpracticable to use is not `.required in order to fully explain the process and enable those skilled in the art to satisfactorily practice it.

The rosin vapors are carried off bya pipe Z through a succession of fractional condensers, which may be of any number, preferably three or four. Three are shown and marked n, 0 and p. Each condenser is maintained at a predetermined temperature by means of a surrounding jacket 'g in which heated oil isv circulated. It is preferred to maintain the three condensers n, o and p (where three" are used) atV temperatures of 400 F., 350 F. and 300 F. respectively.

A high degree of vacuum seems essential to successful-rosinu distillation. -A vacuum of twenty-eight inches of mercury column (if the normal atmospheric pressures about thirty inches) has been used successfully. It is obvious that with a still higher degree of vacuum the minimum temperature o't' distillation may belowered (say 25 F.) When the vacuum drops below twenty-seyen inches at the atmospheric pressure specified, the dis-- tillation is sluggish. With lower atmospheric pressure, the degree of vacuum would be correspondingly higher. Leakage of air (or oxygen) into the still or condensing system should be avoided, as its eiect is to discolor the jro'sin. The temperature ot' the superheated steam admitted through pipe m into the` still should be quite 'close to that maintained in the still.

Rosin condensed in the first condenser n is of excellent color and of such hi h quality, both physically and chemically, tiat it can be used for sizing the highest grade paper, for making the best varnish, and for other purposes. The rosin condensed inthe second condenser ois of good quality and commands a substantially higher price than the rosin inroducedjinto the system. The rosin conldensed in the last condenser p is inferior in quality to that condensed in the otherl condenser?. To produce really high'grade rosin, the temperature of. the condenser should not be less than 350 F. and should be nearer 400 F. At this temperature is produced a waterfree product comparatively free from rosin oil and pine oil, and there is little danger of the condensed rosin crystallizing. By iiicreasing the number of condensers, or by heating the condensers to temperatures different from the temperatures herein specified, or by both means, smaller proportion of the very highest grade rosin, or a larger proportion of rosin of somewhat lower, but still high', grade may bevsecured. The number of con densers and the temperature regulation will depend upon the grade of rosin that it is desired to get and particularly the purpose tor which the rosin is intended to be used.

The rosin and rosin oil vapors that escape from the last condenser pass to the solvent scrubber shown. These vapors, which are essentially. a mixture of rosin and rosin oil, probably do not amount to over two or three per cent of the rosin distilled. The vapors pass through the return bend pipe condenser 1',whieh is Water-cooled by means of a distributor s. A recirculating stream of solvent (gasoline or kerosene) is maintained inside of thecondenser pipes. Without this hydrocarbon solvent, the rosin that would condense inthe pipes 1' would not be in suieieiit qualitjity or sufiiciently Huid to How freely. l )urY ing any single traverse of the condenser pipes, the solvent dissolves much less rosin and rosin vapor than it is capable of dissolving, and it is therefore recireulated until it becomes saturated. The solutionpf hydrocarbon oil and rosin and rosin oil, mixed with water of condensation, passes to a solvent settling or 'separating tank t, wherein the water settles to the bottom and is withdrawn through the valved pipe u. The hydrocarbon oil, with rosin and rosin oil dissolved therein, overflows into a pipe o and, by means of a pump fw is returned through apipe m to the pipe condenser 7'. As the solvent becomes saturated it is replaced with fresh'solvent;4

The advantagev of the scrubbing operation is not primarily to save the small quantity 'of rosin or rosin oil'recoverable thereby, but to prevent the condensation of rosin mist in the vacuum lines, which Would result in clogging up the vacuum lines and prevent regular operation.

The vacuum in the apparatus niay be maintained by connecting the settling tank t,

' through pipe o, with vacuum.

The main advantages of our process arise from the preheating and preliminary distillation (preferential) of the rosin, the fractional condensation, the condensation at a temperature above 350 F., and the avoidance of condensation of rosin and rosin oil vapor or mist in the vacuumv lines.

Having now full'y described our invention, what We claim and desire to protect by Letters Patent is:

1. The process of refining Wood rosin which comprises heating the rosin to a temperature within about'500-650 F. while under a Vacuum corresponding to an absolutepressure not higher than about three inches mercury and condensing a portion of the rosin at a.

temperature' not lower than 350 F.-

2. The process of refining rosin which comprises heating the rosin under a vacuum correspondingto an absolute pressure not higher than about three inches mercury'and to a temperature within about G-650 F. and fractionally condensing'the rosin at a plurality of temperatures adapted to` yield rosin of fractionally condensing the rosin at temperatures varying fromV about 400 F. to about 300 F.

5. The process of refining rosin which comprises heating the rosin under a vacuum corresponding to an absolute pressure not higher than about three inches mercury and to a temperature of 55C-600 F. and fractionally condensing the rosin at temperatures of about 400 F., 350 F. and 300 F.

6., The process of refining rosin which comprises preheating the rosin to a temperature substantially above its melting point and sufficiently high to drive ofi' lower boiling coloring matter and condensing such coloring matter, heating the rosin from which such coloring matter has been removed to a still higher temperature within about i300-650 F. and under a vacuum corresponding to an absolute pressure not above about three inches mercury, and condensing a, portion of the rosin at a temperature substantially above 350 F.

7. The process of refining rosin which includes preliminarily heating'it to a temperature substantially above its melting point and suiiiciently high to drive oflr1 lower boiling point coloring matter and condensing such coloring mattervaporizing the rosin from which coloring matter has been removed by heating it under high vacuum to a substantially'higher temperature than that ot the preliminary distillation and fractionally condensing the vapori'zed rosin.

8. In the process of refining rosin the steps which include establishing an endless circulation of a hydrocarbon a solvent of 'rosin and during such circulation vaporizing rosin by heat under high vacuum, condensing part of the vapors for the recovery of high grade rosin and passing the uncondensed vapors into the circulating solvent until it approaches saturation.

9. The process of refining rosin which comprises heating the rosin under a high vacuum to a temperature within about 500650 F., condensing at least a portion of the rosin at a temperature not less than 350 F., and absorbing at least some of the rosin that does not condense at that temperature into a liquid hydrocarbon solvent.

10. The process of refining rosin which comprises heating the rosin under a high vacuum to a temperature within about 500i-650 F., fractionally condensing the\rosin at a pluralit of temperatures the higher ol which is su st antially above 350 F., and eliminating the relatively small fraction ol rosin and rosin oil mist or vapor from the condensing system by absorption thereof in a liquid hydrocarbon solvent therefor, thereby avoiding the plugging of the` vacuum line by the condensation of the relatively small fraction of said rosin and rosin oil that is not fractionally condensed.

11. The process of refining ,rosin,wl1ich comprises preliminarily heating the rosin v under a vacuum to a temperature substantially above its melting point and sufficientlyv high to drive ofi lower boiling point coloring matter, vaporizing rosin from which such Y coloring -matter has been removed byheating it under a high vacuum to a substantially higher temperature than that ofthe preliminary distillation heat, fractionally connot fractionally condensed by absorption thereof in a liquidhydroearbon solvent therefor to avoid the plugging of the vacuum line. l2. The process of refining rosin which comprises preliminarily heatingthe rosin to a temperature below 500o F. and suiclently above its melting point to drive o" lower boil-- ing point coloring matter and condensing suchcoloring matter, vaporizing rosinv from l which such coloring matter' has been removed by heating it to a temperature substantially above the temperature of the preliminary heat but not above about 650 F. and fractionally condensing the vaporized rosin, the lowesttemperature of condensation being at least 350 F.; said operations being conducted under a vacuum corresponding to an absolute pressure not higher than about three inches i mercury.

In testimony of which invention, we have hereunto set our hands, at Kenvl, N. J., on this 11th day of April, 1923.

HARRY E. KAISER. ARTHUR LANGMEIER. 

